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Big-wheeled Bikes Breed Dedicated Suspension

Published July 15, 2011

By Jason Norman

As the popularity of 29ers continues to rise, engineers are drawing up new suspension platforms better tailored to fit their larger wheel size.

Yeti, which recently unveiled its new SB-66 chassis based on the Switch suspension platform (see sidebar, page 18), is working on a 29er version. And Niner’s CVA suspension, though on the market for five years, recently was awarded a patent.

Yeti owner Chris Conroy said that 29ers are still relatively new to the market so engineers are applying existing solutions to the wheel size, but that may soon change.

“With any progression people start with what they recognize and have used in the past, and tweak that for the larger wheel size,” Conroy said. “But I think it’s entirely reasonable that long term, people will look at suspension technologies specific for bigger wheels.”

“Right now people are trying to establish themselves in the 29er fork market first, and the innovation will take off from there,” Conroy added.

One longtime proponent of 29er-specific suspension is Niner Bikes. The Torrance, California, company committed early on to the category, launching as a 29er-only company in 2004. Its Constantly Varying Arc (CVA) suspension is tailored for 29ers.

Niner president Chris Sugai claims it’s around big wheels. But he admits that CVA was first tested on a 26-inch bike to compare it against suspension systems currently on the market.

“Then we began working on suspension exclusive around 29 and how to best adapt it around a 29-inch wheel,” said Sugai. Among the considerations are different pedal forces and a bottom bracket that sits much lower than the axles.

Sugai believes there’s a market and need for 29er-specific platforms. “I think a suspension system has to be carefully thought out when you’re adapting it to a 29-inch wheel,” he said.

For most companies, 29er-specific suspension is still in the development process, as these bikes present a host of challenges, including chainstay length and bottom bracket height.

“Any suspension system that allows the flexibility to easily design around those challenges has an advantage,” said David Earle, co-founder of the Sotto Group, which offers design and engineering services for suspension and drivetrain development. His company is licensing Switch suspension to Yeti.

Earle said that due to the larger wheel size, kinematic parameters within a specific system need to be optimized around different values than a 26-inch wheel to ensure the bike rides well.

“A lot of the engineers are still figuring out the sweet spots for all of the kinematic parameters,” Earle said. “We have a very good system to calculate what all of those parameters need to be. I recently rode the Yeti Switch 29er in Colorado. It’s really fantastic and will be a game changer.”

Still, whether differences are substantial enough to call for a completely new suspension platform is a point of contention. Trek director of suspension technology Jose Gonzalez said 29ers potentially benefit from different leverage curves. But, “anyone that tries to tell you that it requires a specific suspension platform—it’s marketing smoke to be honest with you,” Gonzalez said.

Late last year Trek was awarded a patent for its Active Braking Pivot (ABP) suspension featured on all of its performance mountain bikes, including 29ers.

Sugai still firmly believes that his CVA suspension—found on all of Niner’s full-suspension bikes—is unique enough to provide a better ride quality. And he said he would entertain the idea of licensing it to other brands.

“The dozens of positive reviews we have received around the world support CVA as the premier 29er suspension option,” Sugai said. “Our commitment to 29ers only enables us to refine the system for our chosen wheel size.”